如何在硒中使用硒wait.until与锚元素

Question

i have selenium project written in c# and i want to migrate it to java, but i have a problem that i could not solve by myself. lets say i have a webElement elem1 and i want to find another element elem2 using elem1 as the anchor. so in java i can do it like that:

WebElement elem1 = wait.until(ExpectedConditions.presenceOfElementLocated(By.cssSelector("div.uiContextualLayer.uiContextualLayerBelowLeft"))) ;

WebElement elem2 = elem1.findElement(By.tagName("li"));

now, my problem starts when i want to do the same but with wait.until() for elem2 . the thing is that elem1 is always appear in the DOM, but elem2 will appear in the DOM only after some time (it depends on some code that is not relevant for this issue), so using the above code will throw an exception. in c# i used lambda expression and it was very simple:

IWebElement elem1 = wait.Until((d) => { return d.FindElement(By.CssSelector("div.uiContextualLayer.uiContextualLayerBelowLeft")); });

IWebElement elem2= wait.Until((d) => { return **elem1**.FindElement(By.TagName("li")); });

in java i cant find a way to do the wait.until AND use elem1 as the anchor for the findElement function. here is a sample of the html i'm working on:

<div class="uiContextualLayer uiContextualLayerBelowLeft">
      <div style="width: 240px;">
          <div class="uiTypeaheadView uiContextualTypeaheadView">
              <ul id="typeahead_list_u_jsonp_2_2" class="search" role="listbox">
                  <li id="js_2" class="user" aria-label="whatEver" role="option" aria-selected="false">
                      <a href="someLink" rel="ignore" target=""> … </a>
                        </li>
                    </ul>
                </div>
            </div>
        </div>
    </div>  
</div>

i don't want to get all the elements that has the "li" tagName into a list and than go over each element to find the element i need. i'm pretty sure i'm missing something which is very basic, and would appreciate any suggestion/explanation.

Answer 1

The most Java-style way is to have methods that return locators and write your own inline ExpectedCondition that uses these methods.

public By getElem1Locator() {
    return By.cssSelector(....);
}
public By getElem2Locator() {
    return By.tagName(....);
}

...

    WebElement elem2 = wait.until(new ExpectedCondition<WebElement>() {
        public WebElement apply(WebDriver driver) {
            try {
                return driver.findElement(getElem1Locator()).findElement(getElem2Locator());
        } catch (NoSuchElementException e) {
            return null;
        }
    });

...

The reason why we want to use locators and not final WebElement instances is that if DOM changes while we are waiting, the WebElement can become stale.

A quick and dirty solution is to use a single Xpath selector for the second element

WebElement elem2 = wait.until(ExpectedConditions.presenceOfElementLocated(By.xpath("//div[contains(concat(' ',normalize-space(@class),' '),' uiContextualLayer ') and contains(concat(' ',normalize-space(@class),' '),' uiContextualLayerBelowLeft ')]//li"));

You should also take a look at Page Factory